1. Field of the Invention
The present invention relates to an air pump, and more particularly, to a dual action air pump which can inflate and deflate at the same time and inflate an inflatable object during both up and down stroke to provide continuous discharge of compressed air.
2. Discussion of the Related Art
Children enjoy playing in inflatable toy structures, such as inflatable houses and above-the-ground pools. Conventional inflatable toy structures are inflated by using a manual or foot operated air pumps. The user of a manual air pump, such as a bicycle tire pump or inflatable toy pump, generally encounters difficulties in inflating a pneumatic article, such as a toy structure or tire. When commencing the pumping process, the article has a low (ambient) or no pressure and it is desirable to pump as large a volume of air as possible into the article with each pumping stroke. The user's difficulty at this stage is that many pumping strokes are required unless the volume of air per stroke is large. Conventional single action air pumps discharge the air inside through the air outlet only during the down stroke of the piston shaft. During the upstroke of the piston shaft, outside air is sucked into the air pump through an air inlet but no air is discharged through the air outlet.
Most manual or foot operated air pumps use the check valve concept to control the flow of air into their reservoirs and the subsequent discharging or exhausting of the air from the reservoir into the object being inflated. Check valves are necessarily provided in the air inlet and air outlet in order to control the air flow in a single direction. As an example, foot operated bellows pumps are normally spring loaded and operate with one intake and one exhaust check value. During the compression of the bellows air chamber (or reservoir) air exhausts into the object being inflated and during the spring-back, or up cycle, air refills the reservoir.
Additionally, it is a common manual air pump industry design to have this type of air pump inflate, but not deflate, an object on both the up and down strokes of the pumping cycle. These types of air pumps are commonly referred to as a double or dual action air pumps, and normally have their reservoir cylindrically shaped with intake check valves located at the opposite ends of the cylinder. As the pumping stroke drives the air out of either end of the cylinder, the opposite side check valve opens to allow the opposite side air to be replenished. During the pumping action where air on either side of a piston head is being compressed, the compressed air inflates the intended object by flowing through a side slit in a hollow piston shaft to which a hose is attached that is connected to the object to be inflated.